//
// ********************************************************************
// * License and Disclaimer                                           *
// *                                                                  *
// * The  Geant4 software  is  copyright of the Copyright Holders  of *
// * the Geant4 Collaboration.  It is provided  under  the terms  and *
// * conditions of the Geant4 Software License,  included in the file *
// * LICENSE and available at  http://cern.ch/geant4/license .  These *
// * include a list of copyright holders.                             *
// *                                                                  *
// * Neither the authors of this software system, nor their employing *
// * institutes,nor the agencies providing financial support for this *
// * work  make  any representation or  warranty, express or implied, *
// * regarding  this  software system or assume any liability for its *
// * use.  Please see the license in the file  LICENSE  and URL above *
// * for the full disclaimer and the limitation of liability.         *
// *                                                                  *
// * This  code  implementation is the result of  the  scientific and *
// * technical work of the GEANT4 collaboration.                      *
// * By using,  copying,  modifying or  distributing the software (or *
// * any work based  on the software)  you  agree  to acknowledge its *
// * use  in  resulting  scientific  publications,  and indicate your *
// * acceptance of all terms of the Geant4 Software license.          *
// ********************************************************************
//
//
/// \file SpinTracking/src/PrimaryGeneratorAction.cc
/// \brief Implementation of the SpinTracking::PrimaryGeneratorAction class

#include "PrimaryGeneratorAction.hh"

#include "G4LogicalVolumeStore.hh"
#include "G4LogicalVolume.hh"
#include "G4Box.hh"
#include "G4RunManager.hh"
#include "G4ParticleGun.hh"
#include "G4ParticleTable.hh"
#include "G4ParticleDefinition.hh"
#include "G4SystemOfUnits.hh"
#include "G4IonTable.hh"
#include "Randomize.hh"
#include "G4ThreeVector.hh"


namespace SpinTracking
{

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......
PrimaryGeneratorAction::PrimaryGeneratorAction(EventAction* eventAction)
    : fEventAction(eventAction) {
  G4int n_particle = 1;
  fParticleGun  = new G4ParticleGun(n_particle);
  // default particle kinematic
  G4ParticleTable* particleTable = G4ParticleTable::GetParticleTable();
  G4String particleName;
  //He3
  // G4ParticleDefinition* He3 = G4IonTable::GetIonTable()->GetIon(2, 3, 0);
  // fParticleGun->SetParticleDefinition(He3);

    G4ParticleDefinition* particle
      = particleTable->FindParticle(particleName="proton");     //or anti_proton
  fParticleGun->SetParticleDefinition(particle);
  fParticleGun->SetParticleMomentum(1.232*GeV);   //proton 1.232 GeV     lambda 1.07GeV(J/psi 3096)  lambda 1.466GeV(Psi 3686)
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

PrimaryGeneratorAction::~PrimaryGeneratorAction()
{
  delete fParticleGun;
}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

void PrimaryGeneratorAction::GeneratePrimaries(G4Event* anEvent)
{
    // random position
    G4double size = 0; 
    G4double x0 = 0;
    G4double y0 = 0;
    G4double z0 = 0;
    fParticleGun->SetParticlePosition(G4ThreeVector(x0,y0,z0));
    
    G4int eventID = anEvent->GetEventID();
    //random direction
    // G4double theta0 = 22;  //degree
    // G4double theta = eventID * 0.1 + theta0;
    //           theta = theta/180 *  CLHEP::pi;
    G4double theta0 = CLHEP::pi/2;
    G4double theta = theta0;
    G4double phi = 0; //G4double(90)/180 * CLHEP::pi;
    G4double xDir = std::sin(theta) * std::cos(phi);
    G4double yDir = std::sin(theta) * std::sin(phi);
    G4double zDir = std::cos(theta);
    G4ThreeVector momentum(xDir, yDir, zDir);
    fParticleGun->SetParticleMomentumDirection(momentum);
  
    //-----------------------polarization direction--------------------------
    //1.parallel to monmentun plane
    G4ThreeVector InitialSpin(0, 1, 0);
    fParticleGun->SetParticlePolarization(InitialSpin);   // y axis

    //2.parallel or vertical to monmentun
    // fParticleGun->SetParticlePolarization(momentum);           //parallel to momentum
    // G4ThreeVector InitialSpin(momentum);

    // G4ThreeVector ver_momentum = momentum.orthogonal().unit();  
    // fParticleGun->SetParticlePolarization(ver_momentum);       //vertical to momentum
    // G4ThreeVector InitialSpin(ver_momentum);
    //-------------------------------------------------------------------------

  fParticleGun->GeneratePrimaryVertex(anEvent);
  fEventAction->AddInitialMomentum(xDir, yDir, zDir);         //lvxr
  fEventAction->AddInitialSpin(InitialSpin.x(), InitialSpin.y(),InitialSpin.z());   //lvxr

}

//....oooOO0OOooo........oooOO0OOooo........oooOO0OOooo........oooOO0OOooo......

}


